Electrostatic chuck

Abstract

According to one embodiment, an electrostatic chuck includes a ceramic dielectric substrate having a first major surface placing an object to be processed and a second major surface on an opposite side of the first major surface, and a base plate provided on a side of the second major surface and supporting the ceramic dielectric substrate. The base plate includes a first communicating passage passing a medium which adjusts a temperature of the object to be processed. The first communicating passage has an upper surface, a side surface, and a lower surface. A ratio of variation of a maximum height Sz in the upper surface to a height of the first communicating passage is not more than 1%.

What is claimed is: 
     
       1. An electrostatic chuck, comprising:
 a ceramic dielectric substrate having a first major surface placing an object to be processed and a second major surface on an opposite side of the first major surface; and 
 a base plate provided on a side of the second major surface and supporting the ceramic dielectric substrate, 
 the base plate including a first communicating passage for passing a medium which adjusts a temperature of the object to be processed, 
 the first communicating passage having an upper surface, a side surface, and a lower surface, 
 wherein a ratio of variation of a maximum height Sz in the upper surface to a height of the first communicating passage is not more than 1%, 
 and wherein the variation of the maximum height Sz in the upper surface, a variation of a maximum height Sz in the side surface, and a variation of a maximum height Sz in the lower surface are different from one another. 
 
     
     
       2. The electrostatic chuck according to  claim 1 , wherein:
 the base plate includes a first portion on a side of the second major surface, and a second portion provided below the first portion and joined to the first portion, 
 and a junction of the first portion and the second portion is located below a center in a vertical direction of the first communicating passage. 
 
     
     
       3. The electrostatic chuck according to  claim 1 , wherein the variation of the maximum height Sz in the upper surface is smaller than the variation of the maximum height Sz in the side surface. 
     
     
       4. The electrostatic chuck according to  claim 1 , wherein the variation of the maximum height Sz in the upper surface is smaller than the variation of the maximum height Sz in the lower surface. 
     
     
       5. The electrostatic chuck according to  claim 1 , wherein
 the side surface includes
 a first region on a side of the second major surface, and 
 a second region located below the first region, 
 
 variation of a maximum height Sz in the first region is smaller than variation of a maximum height Sz in the second region. 
 
     
     
       6. The electrostatic chuck according to  claim 1 , wherein
 the side surface includes
 a first region on a side of the second major surface, and 
 a second region located below the first region, 
 
 variation of a maximum height Sz in the first region is smaller than variation of a maximum height Sz in the lower surface. 
 
     
     
       7. The electrostatic chuck according to  claim 1 , wherein
 the side surface includes
 a first region on a side of the second major surface, and 
 a second region located below the first region, 
 
 a concentration of aluminum in a material of the first region is higher than a concentration of aluminum in a material of the second region. 
 
     
     
       8. The electrostatic chuck according to  claim 1 , wherein
 one of the lower surface and a region below the side surface is a turbulent flow promotion portion. 
 
     
     
       9. The electrostatic chuck according to  claim 1 , wherein
 a material of the upper surface is same as a material inside the base plate. 
 
     
     
       10. The electrostatic chuck according to  claim 1 , wherein the height of the first communicating passage is longer than a width of the first communicating passage. 
     
     
       11. The electrostatic chuck according to  claim 10 , wherein a ratio of the height of the first communicating passage to the width of the first communicating passage is larger than 1 and less than 6. 
     
     
       12. The electrostatic chuck according to  claim 1 , wherein
 a ratio of a distance between an upper surface on the second major surface side of the base plate and the upper surface of the first communicating passage to the height of the first communicating passage is not less than 0.1 and not more than 10. 
 
     
     
       13. The electrostatic chuck according to  claim 1 , wherein
 the first communicating passage further includes a curved connection portion connecting the upper surface and the side surface. 
 
     
     
       14. The electrostatic chuck according to  claim 1 , wherein
 the first communicating passage includes
 a first space on a side of the second major surface, and 
 a second space below the first space, 
 
 a width of the second space becomes narrow toward below. 
 
     
     
       15. The electrostatic chuck according to  claim 1 , wherein
 the base plate includes
 a first portion, 
 a third portion provided above the first portion and joined to the first portion, and 
 a second communicating passage provided between the first portion and the third portion, the second communicating passage passing a gas medium different from a medium flowing through the first communicating passage, 
 
 the second communicating passage is provided on a side of the second major surface from the first communicating passage. 
 
     
     
       16. The electrostatic chuck according to  claim 15 , wherein
 a junction of the first portion and the third portion is located below a center in a vertical direction of the second communicating passage, 
 the second communicating passage includes
 a third space on a side of the second major surface, and 
 a fourth space below the third space, 
 
 a width of the fourth space becomes narrow toward below. 
 
     
     
       17. The electrostatic chuck according to  claim 15 , wherein
 the base plate further includes
 a third portion provided above the first portion and joined to the first portion, and 
 a second communicating passage provided between the first portion and the third portion, a gas medium flowing through the second communicating passage, 
 
 a junction of the first portion and the third portion is located below a center in a vertical direction of the second communicating passage. 
 
     
     
       18. An electrostatic chuck, comprising:
 a ceramic dielectric substrate having a first major surface placing an object to be processed and a second major surface on an opposite side of the first major surface; and 
 a base plate provided on a side of the second major surface and supporting the ceramic dielectric substrate, the base plate being made of a metal, 
 the base plate including a first communicating passage passing a medium which adjusts a temperature of the object to be processed, 
 the first communicating passage having an upper surface, a side surface, and a lower surface, and 
 variation of a maximum height Sz in the upper surface being smaller than variation of a maximum height Sz in the side surface. 
 
     
     
       19. The electrostatic chuck according to  claim 18 , wherein a ratio of the variation of the maximum height Sz in the upper surface to a height of the first communicating passage is not more than 1%. 
     
     
       20. An electrostatic chuck, comprising:
 a ceramic dielectric substrate having a first major surface placing an object to be processed and a second major surface on an opposite side of the first major surface; and 
 a base plate provided on a side of the second major surface and supporting the ceramic dielectric substrate, 
 the base plate including a first communicating passage for passing a medium which adjusts a temperature of the object to be processed, 
 the first communicating passage having an upper surface, a side surface, and a lower surface, 
 wherein a ratio of variation of a maximum height Sz in the upper surface to a height of the first communicating passage is not more than 1%, 
 and wherein a material of the upper surface and a material of the lower surface are different from each other. 
 
     
     
       21. The electrostatic chuck according to  claim 20 , wherein
 a concentration of aluminum in the material of the upper surface is higher than a concentration of aluminum in the material of the lower surface.